The quality of medical engineering and medical equipment need to be enhanced continuously, accompanied by the development of science and technology. Regarding the aspect of wheelchair skill related to health care, how to pursue the further enhanced safety for wheelchair users at the lowest cost is the goal that every manufacturer should be eager to accomplish. Currently, there are many aids designed for people with physical disabilities on the market, and manual wheelchairs and motorized wheelchairs are the most popular among handicapped people who are temporarily or permanently disabled. However, it has been reported in one study that 53.9% of wheelchair accidents involve the wheelchair overturning, among which up to 75.6% involve the wheelchair tumbling either forward or backward, resulting in injuries to 56.6% of wheelchair users (Chan-Chia Chang, Graduate Institute of Occupational Therapy at National Taiwan University, 2009).
A survey of various wheelchairs on the market reveals that only higher-priced wheelchairs are designed with features that prevent the wheelchair from toppling backward. Typical manual and low-priced motorized wheelchairs do not have any method to prevent the wheelchair from toppling backward. Please refer to FIG. 1, which shows a user 11 riding in a wheelchair 12. Wheelchair users may not be aware of the risk posed by a change in elevation (e.g. stairs going downward 10) largely because the user's position in the wheelchair and the inability to turn the head creates a significant blind spot to the rear. As such, wheelchair safety has substantial room to improve, and a device that can detect the road conditions behind the wheelchair is urgently needed.
The problems with the wheelchair rear blind spot amid mixed elevations are solved in the present invention. The inventors conducted experiments, tests and research to devise an early-warning method and device to prevent a wheelchair from toppling over, which not only resolves the drawback of the wheelchair rear blind spot but also promotes wheelchair safety by alerting the user to elevation changes in time to prevent an accident. Furthermore, the present invention overcomes the problems that the scanned laser light pattern needs to be matched and the laser light generator and image-sensing device need to be attached to the wheelchair itself.